AUTHOR=Chi Xupeng , Javidpour Jamileh , Sommer Ulrich , Mueller-Navarra Doerthe 

TITLE=Tracking Fatty Acids From Phytoplankton to Jellyfish Polyps Under Different Stress Regimes: A Three Trophic Levels Experiment

JOURNAL=Frontiers in Ecology and Evolution

VOLUME=6

YEAR=2018

URL=https://www.frontiersin.org/journals/ecology-and-evolution/articles/10.3389/fevo.2018.00118

DOI=10.3389/fevo.2018.00118

ISSN=2296-701X

ABSTRACT=<p>The impacts of biochemicals driving food web processes are under investigation for just the last few decades. In addition, as jellyfish are drawing increasing attentions because of their mass developments and of their potential capacity of driving food web structures and energy flow by “top-down” and “bottom-up” controls. We here show that the provision with the biochemical complex thiamin (vitamin B<sub>1</sub>) to the common phytoplankton <italic>Rhodomonas baltica</italic> altered its fatty acid (FA) pattern toward ω3-highly-unsaturated FAs (ω3-HUFA) and that this pattern was further transferred up to the zooplankton consumer, the copepod <italic>Acartia tonsa</italic>. However, polyps of the Jellyfish <italic>Aurelia aurita</italic> feeding on <italic>A. tonsa</italic> only had a low relative ω3-HUFA content, especially due to a reduction in 22:6ω3 (DHA), but elevated levels of 20:4ω6 (ARA). The high proportion of the ω-6 HUFA, ARA in polyps may provide evidence for preferential conversion of ARA in polyps, eventually from DHA in a so far unknown pathway. In contrast to <italic>A. tonsa</italic>, newly hatched <italic>A. salina</italic> nauplii used as food for <italic>A. aurita</italic> polyps were almost devoid of HUFA, but contained high levels of C<sub>18</sub> polyunsaturated FAs (C<sub>18</sub>-PUFA). Consequently, polyps feeding on them contained few HUFA, while high levels of C<sub>18</sub>-PUFA predominated. This suggests that <italic>A. aurita</italic> polyps cannot efficiently convert ω3 C<sub>18</sub>-PUFA to ω3-HUFA. In addition, besides a decrease in saturated FAs, especially an increase in HUFA in <italic>A. aurita</italic> polyps with decreasing temperature was observed, for which the dietary provision with HUFA seemed to be critical. Altering the FA pattern as a response of temperature reflects an adaptation to seasonal changes and may be related to their life history plasticity.</p>